1. Field of the Invention
The present invention relates generally to a washing machine having at least one balancer, and more particularly to a washing machine having at least one balancer capable of reducing a manufacturing cost and an assembly time, and allowing the balancer assembled to a spin tub to be easily replaced.
2. Description of the Related Art
In general, washing machines do the laundry by spinning a spin tub containing the laundry by driving the spin tub with a driving motor. In a washing process, the spin tub is spun forward and backward at a low speed. In a dehydrating process, the spin tub is spun in one direction at a high speed.
When the spin tub is spun at a high speed in the dehydrating process, if the laundry leans to one side without uniform distribution in the spin tub or if the laundry leans to one side due to the abrupt acceleration of the spin tub in an early stage of the dehydrating process, the spin tub undergoes a deviation between the center of gravity and the center of rotation to thus cause noise and vibration. The repetition of this phenomenon causes parts, such as a spin tub and its rotating shaft, a driving motor, etc., to break or causes a reduction in the life span of the parts.
Particularly, a drum type washing machine has a structure in which the spin tub containing laundry is horizontally disposed, the spin tub is spun at a high speed in the state where laundry is collected on the bottom of the spin tub by gravity in the dehydrating process, so that the spin tub undergoes a deviation between the center of gravity and the center of rotation to have a high possibility of causing excess noise and vibration.
Thus, the drum type washing machine is typically provided with at least one balancer for maintaining a dynamic balance of the spin tub. The balancer is equally applied to an upright type washing machine in which the spin tub is vertically installed.
An example of a washing machine having ball balancers is disclosed in Korean Patent Publication No. 1999-0038279. The ball balancers of a conventional washing machine include racers installed on the top and the bottom of a spin tub in order to maintain a dynamic balance when the spin tub is spun at a high speed, and steel balls and viscous oil are disposed and freely move in the racers.
Thus, when the spin tub is spun without maintaining a dynamic balance due to an unbalanced eccentric structure of the spin tub itself and a lopsided distribution of the laundry in the spin tub, the steel balls compensates for this unbalance, and thus the spin tub can maintain the dynamic balance.
However, the conventional washing machine has a structure in which an entire circumferential edge of each ball balancer is seam-welded to the spin tub, so that the spin tub forms part of the surface of each ball balancer, or a structure in which each ball balancer includes upper and lower plates fused to each other, thereby requiring a high manufacturing cost and long assembly time, which lowers mass productivity.
Further, the conventional washing machine has a structure in which each ball balancer coupled to the spin tub cannot be replaced with a new one, thus necessitating discarding the entire spin tub when any ball balancer is determined to be a failure in a quality inspection.
In addition, each ball balancer of the conventional washing machine has an irregularly stepped structure because fusion scraps are generated around a long fusion portion (or a long seam portion) formed along a path of motion of balls during fusion, so that the balls generate unnecessary noise and vibration while moving along the fusion portion.